1. Field
The present disclosure pertains to the field of information processing, and more particularly, to the field of testing information processing systems for reliability.
2. Description of Related Art
Margin testing may be used as a valuable tool to improve the reliability, availability, and serviceability of information processing systems. Margin testing involves testing microprocessors and other system components across a range of operating conditions, such as input voltage and clock frequency, to determine the margin between the conditions at which the components are designed to operate and the conditions at which they fail. Special test patterns may be run in order to exercise as many transistors and nodes as possible. Margin testing may also involve comparing margins before and after stressing the components, to determine whether the stress causes the margins to decrease. Low margins or margins that decrease significantly due to stress may be a sign of manufacturing or other defects that may cause a component to degrade more rapidly than expected. Therefore, component manufacturers may use margin testing to screen out components that might otherwise be built into systems, degrade rapidly as the system is used, and then fail intermittently or catastrophically, thereby reducing the system's reliability, availability, and serviceability.
As feature dimensions in components used in information processing systems decrease, the components become more susceptible to degradation and failure due to the effects of hot electrons and dielectric breakdown. Therefore, even components that have been margin tested before being built into a system may fail prematurely. To attempt to identify these components before they fail, it may be desirable to be able to margin test components after they have been built into a system and put into operation (“in situ”).